Machine tools, such as automatic lathes, automatic multiple spindle machines, chucking machines, and other forms of machine tools in which a work piece is rotated while being operated upon by various forming, drilling and other cutting tools, commonly use a non-rotating tool that is moved transversely into the rotating work piece for effecting operations such as turning, forming, grooving, sidemilling and/or cut-off of the finished piece from a bar of the raw material. Because these operations by non-rotating tools are time consuming, and in the case of cut-off, usually make a relatively wide cut and thereby waste metal, attachments have been developed for performing these operations with rotary cutting tools. Such attachments employ either electric motor driven shafts or mechanical drives from a power take-off shaft of the machine for imparting rotation to the cutting tool. Such attachments are costly and bulky.
Although a rotary cutting tool attachment that is driven by a hydraulic motor is disclosed in U.S. Pat. No. 2,301,028, such attachments heretofore have had little or no acceptance in industry. It is believed that a major reason for this is that such hydraulic attachment utilizes a belt drive between a hydraulic motor and the rotating tool and which belt drive is exposed to oil or other cutting fluids which could cause slippage and rapid deterioration of the belts. Furthermore, to encase the belt would require a bulky housing which would limit the usefulness of the attachment.